=Pressure pieces.=--Name all the pieces of an engine through which the steam pressure is received and transmitted. II. 446.

=Horse-power.=--What is the unit or measure of horse-power? What is the meaning of nominal horse-power? II. 446.

=Lost vacuum.=--Name all the causes from which the vacuum may become defective or lost. II. 447.

=Hot journals.=--What are the princ.i.p.al causes of the heating of engine journals? II. 447.

=Stays.=--What is a boiler stay? What is a gusset stay? What is a tube stay or a stay tube? II. 452.

=Stress per square inch.=--How much stress is usually allowed per sectional square inch of boiler stay? II. 452.

=Breaking of tubes.=--What is the commonest cause of boiler tubes breaking? II. 452.

=Split tube.=--How is a split tube stopped up? II. 452.

=Uptake.=--What is the uptake of a marine boiler? What is a wet uptake?

II. 453.

=Superheater.=--What is the superheater of a marine boiler? II. 453.

=Fittings.=--What fittings are essential to a marine boiler? II. 453.

=Safety valves.=--What is a dead-weight safety valve? What is a spring-loaded safety valve? What is a lock-up safety valve? II. 453.

=Test c.o.c.ks.=--What do the three boiler test c.o.c.ks show? How are boiler test c.o.c.ks cleaned? II. 453.

=Steam gauges.=--What is a gauge gla.s.s or water-gauge gla.s.s? What is a Bourdon dial gauge? What pressure is shown by a boiler steam gauge? II.

453.

=Sc.u.m c.o.c.ks.=--How many sc.u.m c.o.c.ks are used in a marine boiler? II. 454.

=Sluice valves.=--What are sluice valves in steamships? II. 454.

=Removing scale.=--How is scale removed in boilers? II. 454.

=Salinometer.=--What is a salinometer? II. 455.

=Salt in sea water.=--About how much salt does sea water contain? II.

454.

=Division plates.=--What are division plates in boilers? II. 455.

=Intercepter.=--What is the separator or intercepter of a marine boiler?

II. 455.

=Boiler draft.=--What causes the draft in a boiler? II. 455.

=Rapid wasting.=--Where does the most rapid wasting occur in marine boilers? II. 455.

=Coal consumption.=--About how much coal is consumed per square foot of grate in marine boilers? II. 455.

=Short of coal at sea.=--If at sea and short of coal, what course would you pursue in order to save coal and get into port? II. 455.

=Boiler relief in extreme danger.=--How would you relieve a marine boiler in case of the safety valve being locked down from some accidental cause, the engine also being disabled? II. 455.

=Pressure test.=--At what pressure should a new boiler be tested? II.

456.

=Boiler examination.=--State what you would consider a proper examination, inside and out, of a marine boiler that had been in sufficient service to require examining. II. 458.

APPENDIX--PART II.

DICTIONARY OF WORKSHOP TERMS.

A

=Addendum.= That part of a gear wheel tooth that extends beyond or outwards from the pitch line.

=Addendum-circle.= The circle representing the full or greatest circ.u.mference of a gear wheel.

=Adjustable reamer.= A reamer whose teeth may be adjusted to the required diameter.

=Angle-iron.= A shape of wrought iron or steel having two f.l.a.n.g.es at a right angle; thus, [L]

=Angle-plate.= A plate having surfaces at a right angle, one to bolt to the machine work-table, the work being bolted to the other.

=Angle-tooth.= A gear wheel tooth that runs across the face of the wheel in a line that envelops part of the wheel circ.u.mference.

=Angular cutters.= Cutters, whose teeth are on a circ.u.mferential surface, that is, at an angle to the cutter axis, such angle not being that of 90 to either the side face nor to the axis of the cutter.

=Angular-velocity.= Velocity measured in degrees of angle.

=Annular.= In the form of a ring.

=Ap.r.o.n.= 1. The piece that carries the tool port or clamp on an iron planing machine. 2. The front plate of a lathe carriage.

=Arbor.= 1. A mandrel used to drive work upon. 2. A spindle or shaft of a machine.

=Arc.= A portion of a circle.

=Archimedean drill= (ar-k[)i]-m-[e.]-d[=e]'an) A drilling device in which a nut moved endwise on a stock or handle causes the drill to revolve back and forth.

=Arc of approach.= That part in the revolution of a pair of gear wheels in which the teeth in contact approach the line of centres of the two wheels.